1. Field of the Invention
The invention relates to a device for converting mechanical force to an electrical signal. More particularly, it relates to an arrangement for providing an electrical signal in response to tension in a moving web so that such tension can be monitored and controlled.
2. Discussion of the Prior Art
Because of the importance of maintaining the desired tension in webs of material passing over rolls during processing, various methods and devices have been developed for measuring web tension either directly or indirectly. One type of known web tension measuring arrangement comprises means for sensing the force exerted on a roll such as an idler roll by a web moving over and carried by the roll. Such a device can include a transducer which converts mechanical force on the roll to an electrical signal which can be monitored for manual adjustment of web tension or fed to means for automatic web tension control. Transducers have been mounted both within rolls and in roll shaft supporting joints beyond the ends of rolls.
Strain gages located within roll ends are shown, for example, in U.S. Pat. No. 4,784,004. U.S. Pat. No. 4,052,891 shows a plurality of strain gages mounted beyond a roll end in a housing.
Other arrangements for web tension measurement are shown in U.S. Pat. Nos. 3,260,106; 3,763,701; 4,326,424; 4,674,341; 4,691,579 and Re 31,312, which are mentioned here to show the state of the art.